Apparatus for controlling the flow of hot blast to the tuyeres of blast furnaces



Sept. 15, 1959 J, o o

APPARATUS FOR CONTROLLING THE FLOW OF HOT BLAST TO THE TUYERES OF BLAST FURNACES 4 Sheets-Sheet 1 Filed Aug. 24, 1956 148 15! 149 INVENTOR.

1 4 155 I3 Milchell J. Bake 16;

Sept. 15, 1959 M. J. BOHO 2,904,327

APPARATUS FOR CONTROLLING THE FLOW OF HOT BLAST TO THE TUYERES OF BLAST FURNACES 4 Sheets-Sheet 2 Filed Aug. 24, 1956 I16 12 128 I V I]; 10 9 If! I? 122 11.9 g A HI IHH ll HIIHII H 121 12; as

13:4 INVENTOR.

101 Mikkel] J Boho um 4 A gmAxv BY// g gi yg Sept. 15, 1959 M. J. BOHO 2,904,327

APPARATUS FOR CONTROLLING THE FLOW OF HOT BLAST TO THE TUYERES OF BLAST FURNACES Filed Aug. 24. 1956 4 Sheets-Sheet 3 INVENTOR. Milclzell zl B0110 Sept. 15, 1959 M. J. BOHO 2,904,327

' APPARATUS FOR CONTROLLING THE F LOW OF HOT BLAST TO THE TUYERES 0F BLAST FURNACES Filed Aug. 24, 1956 4 Sheets-Sheet 4 A v r INVE-INTOR. Michell rl Balm Unite 2,9G4,327 Patented Sept. 15, 1 959 APPARATUS FOR CONTROLLING THE FLOW-F ggg lgms'r TO THE TUYERES OF BLAST FUR- Mitchell J. Boho, Mount Lebanon Township, Allegheny County, Pa., assignor to Hagan Chemicals & Controls, Inc., a corporation of Pennsylvania Application August 24, 1956, Serial No. 606,089 8 Claims. (Cl. 266--30) This invention relates to blast furnaces and more particularly an apparatus for effecting substantially equal volumetric flow of the available supply of wind or hot blast to the tuyeres of a blast furnace.

The supply of wind or hot blast for the tuyeres of a blast furnace is delivered to a bustle pipe that encircles or embraces the furnace. In a typical blast furnace there may be anywhere from twenty to twenty-six tuyeres, more or less, each of which is connected by a pipe to the bustle pipe. Because the density or compactness of the charge in a blast furnace may vary from tuyere to tuyere, it has heretofore been difiicult to effect equal or substantially equal volumetric how of hot blast or Wind to each tuyere. Furthermore, the flow to each tuyere is dependent upon the available volumeof wind delivered to the bustle pipe. That available volume whatever it may be must be distributed substantially equally among the tuyeres.

In accordance with the teaching of the invention the volumetric flow through each tuyere pipe is measured across an orifice or equivalent. A damper or Valve is provided in each tuyere pipe for adjusting the flow through it. Because the resistance to flow into the charge at the various tuyeres may differ from tuyere to tuyere as above stated, the distribution of wind or hot blast among the tuyeres is based on the fact that the regulating valve or plug in one of the tuyere pipes should be held in open or nearly fully open position. Thus in accordance with the teaching, the valve or plug in one of the pipes will be set in substantially wide open position to allow the flow to assume whatever value it will take, while the plugs or valves in the other tuyere-pipes are so modulated that the volumetric flow in all of the tuyere pipes will be substantially equal. As the supply to blast to the bustle pipe changes, such flow adjustments are made in all the tuyere pipes that each gets its proportionate share of the total.

An object of the invention is to provide a means of effecting substantially equal volumetric rates of flow of wind or hot blast to the tuyeres of a blast furnace which consists in effecting substantially unobstructed flow to a selected tuyere, modulating the volumetric'flows in the remaining tuyere pipes to a set point, and then adjusting the flows in all the pipes as the supply at the bustle pipe either decreases or increases so all pipes will have substantially equal flows.

Another object of the invention is to provide a control system provided with means for volumetric regulation of flow in each of the tuyere pipes and means for providing substantially unmodulated flow in a selected pipe in which its valve is selected to operate normally at or near substantially wide open position, and means for so modulating the flow in all the pipes with reference to the flow in the selected pipe, that substantially equal flows in all the tuyere pipes are effected.

The novelty of the means and the novel arrangement of the apparatus for practicing the invention are described in the following specification and illustrated in the acprovided with a plurality of tuyeres T to T respectively.

companyingdrawings from which, objects and advantages other than those stated supra, will be apparent to those of ordinary skill in the art to which the invention pertains.

In the drawings: I

Figure l is a more or less diagrammatic view in horizontal-section taken at an elevation above the bustle pipe of a blast furnace, showing a blast furnace provided with a multiplicity of tuyeres and tuyere pipes for supplying hot blast from the bustle pipe to the tuyeres,

and regulating: apparatus for adjusting the flows in the several tuyere pipes to substantial equality;

Fig. 2 is an enlarged view showing aportion of the bustle pipeof Fig. 1 and a group of the tuyere pipes provided with a control system for automatically adjust* ing the flow in the several tuyere pipes to substantial equality;

Fig. 3 is a more or less diagrammatic viewin section of a loaded regulator embodied in the system of Figs. 1 and 2;

Fig. 4 is a more or less diagrammatic View of a loadedgraded regulator embodied in Figs. 1 and 2;

Fig. 5 is an enlarged view of a power cylinder for operating a valve or damper in the tuyere pipes shown in Figs. 1 and 2;

Fig. 6 is a view in longitudinal section of a totalizer embodied in the control system shown in Fig. 2; and

Fig. '7 is a more or less detailed view in section of a ratio-totalizer=embodied in the control system of Fig. 2.

In Fig. 1' of-the drawings a blast furnace 1 is shown The tuyeres are supplied with hot blast or wind through tuyere pipes 2a through 2t, respectively. The tuyere pipes are supplied with hot blast or wind by a bustle pipe 3 As shown, the bustle pipe encircles or embraces the furnace.

The respective tuyere pipes are provided with orifices 4a to-4t, or equivalent, such as venturies. The flows in the respeotivetuyere pipes are measured by loaded, flow measuringand regulating devices 5a to St. The tuyere pipes-are also provided with plug valves shown diagrammatically as dampers 6a to 6t, respectively, and the respective dampers are operated 'by power cylinders or operators-7a to 7t, respectively. Each power cylinder is controlled by its associated regulator; for example power cylinder 7a is controlled by regulator 5a, power cylinder 7b by regulator 5b etc.

The pressure differences across orifices 4a to 4t are impressed on diaphragms, to be described infra, of regulators 511' to Si by pressure connections Pla, PZa, Plb, PZ b etc. to Fit, PZt, as shown.

Each of the regulators 5a to St is provided with means whereby its regulating point may be changed. The regulating points of all the regulators are adjusted with reference to the pressure of the blast supply in the bustle pipe 3, the magnitude of the flow in the selected tuyere pipeand the value of the flows in the other pipes. To illustrate: The available blast in the bustle pipe 3 may be at X pounds pressure; the flow in each of the tuyere pipes at that bustle pipe pressure should be Y cubic feet per minute at the temperature and pressure existing in the bustle pipe. Under those circumstances, the regulators 5a to 51 will so control the operation of the power'cylinders 7a to 7t that the positions of the dampers 6a to6t will maintain a flow of Y cubic feet per minute in each tuyere pipe. If the flow through the selected tuyere pipe 2:: increases or decreases, the flow in the other tuyere pipes should correspondingly be adjusted. This '-is accomplished by cascading the signal outputs of the regulators 5a to St and utilizing the final output of the cascading system to load a regulator whose output is utilized to load and change the regulating points of 3 all the tuyere pipe regulators in the same direction. The final output of the cascading system loads the individual regulators with reference to the pressure in the bustle pipe 3. A description of regulators 5a to St, the power cylinders 7a to 7t, the cascading system and the loading system for the tuyere pipe regulators follows infra.

The regulating system as shown in Fig. 1 is quite schematic and not fully complete, but is shown in a more complete state in Fig. 2. In Fig. 2, a portion of the bustle pipe 3 and a few of the tuyere pipes for example pipes 2a, 2b, 2c and 2t, connected to the bustle pipe are shown. The tuyere pipes between 2d and 2s have been omitted to simplify the disclosure. However, the controls and regulation of the flows in pipes 2d to 2 both inclusive, would be the same as for pipes 2a, 2b, 2c and 2d. Therefore, the portion of the control system illustrated in Fig. 2 will suffice to illustrate the operation of the complete system as diagrammatically shown in Fig. 1. Assuming that tuyere pipe 2a has been selected as the base pipe for control purposes, and that damper 6a is to be regulated at or near wide open position, the cascading begins with regulator 5a. Regulator 5a develops a control force, a pneumatic pressure for example, that varies in accordance with the pressure drop across the orifice 4a. That control force is supplied to the pilot valve of regulators 7a through a pipe 8a. The power cylinder 7a so positions damper 4a, in accordance with the control force that the flow signal would be proportional to the pressure drop. The control force of regulator 5a is also supplied by pipe 8a through a pipe 8a to the pressure signal input side of a totalizer 9a shown in detail in Fig. 6. The totalizer 9a is connected to a supply of signal pressure of constant value P. The pressure P is connected to totalizer 9a through a pipe 101:. The output signal of totalizer 9a is transmitted through a pipe 11a to the supply connection 10b of a totalizer 9b. The output of totalizer 9a thus becomes the supply pressure for totalizer 9b.

The respective regulators 5b to St respond to the pressure differences across the orifices in tuyere pipes 2b to 2t, respectively, and generate control forces that are proportional to those pressure differences. 'The output signals or pressures from the respective regulators are delivered to transmission pipes S'a to 8t, respectively, to the respective pilot valves of regulators 7b to 7t and from pipes 8b to 8!, respectively, through the respective pipes 8b to 8t to the signal input chambers of the respective totalizers 9b to 9t.

The output pressure of totalizer 9a is the supply pres- 1 sure for totalizer 9b, being delivered by pipe 110 to the supply connection 10b of totalizer 9b; the output of totalizer 9b is delivered through pipe 11b to the supply connection 100 of totalizer 9c and so on until finally the output of totalizer 10r (not shown) is supplied through pipe 11s to the supply connection 10t of totalizer 91.

The output of totalizer 9t is supplied through a pipe 11t to a ratio totalizer 12 having rate action and automatic reset characteristics. The output of the ratio totalizer 12 under certain conditions, i.e. when the output pressure of totalizer 9t is above a predetermined value, sends a loading pressure through pipe 13 to the loaded, graded regulator 14.

The term loaded regulator as applied to regulators 5a through St, respectively, means that these regulators operate to maintain a constant condition and that therefore the output pressures may vary over a wide range in bringing the condition back to the regulated point from a given deviation from that point.

The term loaded in loaded regullator means that the regulating point may be changed by imposing a loading pressure for example on the pressure responsive element.

The term loaded graded regulator means that for every value of input pressure there is a definite andfixed value of output pressure, and that the'term. loaded" 4 means that the output range for a given range of input pressures may be modified.

Regulator 14 is connected by a pipe P to the bustle pipe 3. It responds to the pressure in the bustle pipe 3 to so load regulators 5a to St that their regulating points are changed by the same amounts and in the same direction. The loading pressure supplied to regulator 14 by the ratio totalizer 12 changes the regulating point thereof with reference to the pressure in the bustle pipe 3. The loading pressure supplied by totalizer 12 causes regulators 5a to St to regulate the flows in the tuyere pipes 2a to 2! at lower values. When the totalizer 12 does not send a loading pressure to regulator 14, the regulators 5a to St operate to maintain higher flows in the tuyere pipes.

The output loading pressure of regulator 14, as modified by the pressure of totalizer 12 and the bustle pipe pressure, is delivered to the regulators 5a to St through a pipe 15 and branch pipes 15a to 15!, respectively.

Since the pressure outputs of totalizers 9a to 9t can never exceed the pressure at the supply connections 10a to 101 thereof, it follows that the output of these totalizers as delivered to their respective signal pipes 11a to 112 can equal the pressure SP at connection 10a only when the pressure differential across orifice 4a is such as to cause the output pressure of regulator 5a to be equal to the supply pressure SP, and the difierent pressures across orifices 4b to 4t are not only equal to each other, but equal to the difierential across 4a as well. If these differentials are not equal to each other, or if the difierential across an orifice, say orifice 4c, is less than the supply pressure at 100 of totalizer 9c, the output pressure to pipe 11c will be no greater than the pressure in pipes and '0, except and unless totalizer 9c is spring or otherwise loaded to have an output range from a value higher than zero to the value of the supply at as a maximum. The above holds true also for the other totalizers. The net result of the control system is to automatically change the control points of all regulators 5a to 52 from the final output pressure of totalizer 9t and the bustle pipe pressure that each of the regulators 5a to St operating in parallel,

will so control the power cylinders 7a to 7t that the position of the dampers operated thereby will effect equal flows in all the tuyere pipes, tuyere pipe 2a being the base or datum pipe.

The regulators 5a to St are similar in construction and that construction is shown in Fig. 3; the construction of regulator 14 is shown in Fig. 4; the power cylinders 7a to 7t are of the same construction as shown in Fig. 5 and the constructions of the totalizers 9a to 9! being the same, are shown in Fig. 6. The enlarged view of ratio totalizer 12, see Fig. 7, will aid in the understanding of its construction and operation.

The construction and operation of the regulators, the power cylinders and the totalizers follow after which the construction of the ratio totalizer 12 will be given.

The flow measuring and regulating devices 5a to 5! as shown in Fig. 3 each comprise a diaphragm 20, the marginal edge of which is disposed between the mating flanges of housing parts 21 and 22. These mating flanges are bolted tightly upon the marginal edge of the diaphragm 20 to provide pressure receiving chambers 23 and 24. The chamber 23 receives the pressure from the upstream side of an orifice such as orifice 4a through the connection Fla, and the chamber 24 receives the pressure on the downstream side thereof through the connection P2a. The difference in the operative pressures in chambers 23 and 24 is the pressure difference across the orifice to which those chambers are connected. The major portion of. the area of diaphragm 20 is rigidly clamped between backing plates 25 and 26. The diaphragm 20 operates an escapement valve 27 through a linkage comprising a rod 28 that extends upwardly through the housing 21 and is coupled to a C-shaped yoke 29 as shown. In or er to, seal the opening through which the rod 28 extends, a light sealing diaphragm 30 is secured at its marginal edge in pressure tight relationship on the housing 21 and its center is clamped between a pair of nuts 31 on the rod 28. The yoke 29 is connected to a valve 32 within a body 33 of the valve 27. The yoke 29 is also provided with a knife edge 34 that is supported on a beam 36. One end of the beam is supported on a knife edge or fulcrum 37 and the other end is connected by a spring 38 to a lever 39, one end of which is pivoted at 40 in a housing 41. The central portion of the lever 39 is connected by a link 42 to a loading diaphragm 43. The marginal edge of the diaphragm is clamped between mating flanges of housing members 45 and 46. The link 42 as shown is connected rigidly to the diaphragm at its central portion. The diaphragm is urged upwardly by a relatively heavy spring 47. The space within the housing 45 forms a chamber 48 to which the signal pressure delivered to pipes and 15a to 15t of Fig. 2 is delivered. Thus the pressure on the diaphragm 43 varies with the pressure output of the regulator 14 which in turn is proportional to the pressure in the bustle pipe 3 and the output signal pressure in pipe 13 generated by the ratio totalizer 12. The pressure delivered to chamber 48 is resisted by the spring 47 so that for every value of pressure in chamber 48 the lever 40 will take a definite position, either clockwise or counterclockwise about its pivot 40, thereby changing the tension in spring 38.

If the pressure in chamber 48 is zero gauge, a higher pressure difference on diaphragm is required to establish a given output pressure at the outlet of valve 27. As the pressure in chamber 48 increases, the tension in spring 38 is relieved so that the same differential will generate a higher output pressure at valve 27.

The supply pressure to valve 27 is delivered through a pipe 50. That pressure is maintained constant at a predetermined value of P pounds per square inch. The valve 32 is tapered at each end so as to control the inlet port seats 51 and 52, respectively, in the valve body 33. When the Valve 32 is in its uppermost position where the inlet port seat 51 is engaged and closed, the pressure delivered at the outlet of the valve into pipe 8a is a minimum, namely atmospheric, as the outlet port 52 which leads to the atmosphere, is uncovered. When valve 42 is in its lowermost position and closes the outlet port seat 52, the pressure in pipe 8a will be at a maximum and equal to the pressure P in the supply pipe 50. For intermediate positions of the valve 32, the pressure in the signal pipe 8a will vary between atmospheric and maximum in incremental steps.

The device of Fig. 5 is stabilized in its operation by a dash pot 53 which also receives pressure from the output signal pipe 8a as shown. The dash pot is connected to the diaphragm 20 by means of a spring 54, a sealing diaphragm 55 and the rod 28. The sealing diaphragm 55 serves to make the pressure chamber 24 pressure tight at the point where the rod 28 passes out of it. The area of diaphragm 55 is small so that the force developed by the pressure on it will not have any material effect on the operation of the device.

The dash pct 53 comprises a cylindrical member 56 which is a part of a housing 57 that is secured to the diaphragm housing part 22 as shown. The dash pot includes also a bellows 58 that is secured in pressure tight relation to the bottom of the housing 57. Within the bellows 58 is a spring 59 that resists the pressure supplied to a housing 6%? in which the bellows is disposed. The bellows 58 will contract or elongate in proportion to the magnitude of the pressure within the housing 60. The cylinder 56 and the dash pot bellows 58 contains a fluid or liquid 61. The lower end of the spring 54 carries a piston 62 that is acted upon by the fluid in the dash pot. In the cylinder 56 is a by-pass 63, the flow area of which may be restrictively adjusted by means of a needle valve 64.

When the pressure difference between pressures Pla and pressure P2a is increasing so that the diaphragm 20 is pushed downwardly, that downward motion is transmitted to the dash pot piston 62 through the spring 54. The downward motion of the diaphragm 20 also causes valve 27 to deliver an increased pressure to pipe and to the housing 60. Therefore, that pressure acts to compress the bellows 58 and cause the fluid to move the piston 62 upwardly, thereby developing a force that resists the downward motion of the diaphragm 20. As that resisting force persists, fluid from the clash pot flows through the restricted by-pass 63 to the upper side of the piston 62 thereby dissipating the effect of the pressure delivered to chamber of housing 60. The time required for the resisting force to 'be dissipated is sufiicient to give stability to the action of the regulator by preventing over travel of the valve 32 in response to a change in pressure differential (P1aP2a). As the pressures delivered to chamber 48 increase, the pressure difference (Fla-P2a) required to effect a change in signal pressure in pipe 8a from 0 to maximum, also decreases. As the pressure in chamber 48 decreases, the diaphragm 20 is loaded in an upward direction which tends to urge the valve 32 toward the inlet port. Therefore, the pressure change or difference (P1aP2a) required to effect a full change in pressure from 0 to maximum in the signal pipe 8a will increase. Thus the pressure delivered to chamber 48 to diaphragm 43 operates to modify the control point of the regulator.

The loaded graded regulator 14 as illustrated in Fig. 4 differs from the loaded regulators 5a to St in that the dash pot is omitted and in lieu thereof a graded loaded mechanism 53a is substituted for the dash pot mechanism 53.

The graded mechanism comprises a spring 54a secured to a block 54b at the lower end of link 23 and to a block 540 into which is threaded a screw 54d. The screw 54d is secured to the free end of a bellows 58a secured at its upper end to a plate 58b. The plate 58b is clamped between a pressure chamber 60a and the bottom of housing 57 to form a pressure chamber PC. to which the output pressure of valve 27 is delivered. (Parts of the regulator of Fig. 4 which correspond with those of the regulator of Fig. 3 are given the same reference characters with primes aflixed.)

Contraction of the bellows 58a is resisted by a strong spring 59a. When the pressure in the bustle pipe 3 increases, diaphragm 20' moves downwardly, valve 32 moves away from the inlet port 51 and towards the exhaust port 52 thereby increasing the output pressure to pipe 15 and to chamber P.C. That pressure compresses bellows 58a and the springs 59a and 54a. Thus the upward force on the diaphragm 20' is balanced by the compression in spring 54a and the contractive force on bellows 58a is balanced by spring 5%. Therefore, the pressure in the bustle pipe must increase further before the output of valve 27' can be increased. As the pressure in the bustle pipe 3 decreases, diaphragm 20' moves upwardly by tension in spring 38, the valve 27 is actuated to decrease the output pressure to pipe 15 and chamber PC. The bellows 58a therefore expands until the pressure balances spring 59a and spring 54a balances the forces urging diaphragm 20' upwardly. Therefore, for every value of pressure in the bustle pipe there will be a definite and corresponding pressure in the output pipe 15 as delivered to the loading mechanisms of the loaded regulators 5a to St.

As the loaded pressure on diaphragm 43 increases, the tension in spring 38' is relieved; therefore, the output pressure of valve 27' will be higher for the same bustle pipe pressure. Loading diaphragm 43' therefore has the same effect that an increase in bustle pipe pressure would have. That increase in pressure in pipe 15 causes regulators 5a to 5! to operate at regulating points that will position dampers 6a to 6: to more restricted or closed positions. In other words, a higher output pressure in pipe 15 calls for lower flows or decreased flows in the tuyere pipes which can only result by moving the dampers 6a to 6t towards closed position. Whatever the loading pressures on the regulators a to St may be, those regulators will cause the dampers to be so positioned by the power cylinders that the flows in the tuyere pipes will be at the regulated values determined by the loading pressures.

The power cylinders utilized for operating the dampers or valves in the tuyere pipes 2a to 2t are illustrated in Fig. 5. The power cylinder comprises a cylinder 67 in which a piston 68 is disposed. That piston is connected to a piston rod 69. The piston rod carries a frame composed of side bars 70 and 71 and cross bars or cross heads 72 and 73 at the upper and lower ends thereof as shown. The cross head 72 is connected by a link 74 to the crank arm 75 of the damper or valve 4a.

Operation of the power cylinder is controlled by a pilot valve 76. The pilot valve 76 operates in a valve body 77 having an inlet port 78 and outlet ports 79 and 80. The outlet port 79 is connected by a pipe or passage 81 to the upper end of the cylinder 67 and outlet port 80 is connected by a pipe or passage 82 to the lower end of the cylinder. The valve 76 has spaced lands 83 and 84 that control the outlet ports 79 and 80, respectively. The pressure for operating the power cylinder is supplied to the pilot valve by a supply pipe 85. When the valve 76 is in the position shown in Fig. 6 it is in neutral in which case both of the outlet ports 79 and 80 are closed. When valve 76 is moved downwardly so that the outlet port 80 is uncovered, and exposed to the pressure in pipe 85, operating pressure is delivered to the lower end of the cylinder causing the piston to move upwardly. As the piston moves upwardly, pressure medium above the piston is exhausted through passage 81 and the outlet port 79 to the atmosphere. When valve 76 is moved upwardly from its neutral position, pressure is supplied from pipe 85 through passage 82 to the upper end of the cylinder causing the piston 68 to move downwardly. As it moves downwardly pressure is exhausted from the lower end of the cylinder through passage 82, the outlet port 80 and an exhaust port 86.

Increasing pressures delivered to the pilot valve operator from its associated regulator in the So to St series results in the damper operated thereby, being moved towards closed position to reduce the flow in its tuyere pipe. Decreasing values of pressure to the pilot valve means that the tuyere pipe flow is below the regulated point; therefore the pilot valve causes the power cylinder to move the damper to a wider open position. The pilot valve operator comprises a housing 88 having therein a diaphragm 89. The diaphragm is resisted on its lower side by a compression spring 90, the lower end of which is carried in a socket 91. The socket 91 is attached to one arm of a bell crank 92 which is pivotally mounted on a bracket 93 secured to the cylinder 67. The outwardly extending bell crank arm is provided with a cam follower or roller 94 that rides on an angling or compensating bar 95 carried by the side rod 70. The bar 95 and the bell crank 92 act to return the valve 76 to neutral position Whenever the piston has made a stroke of sufficient length in either direction in response to a change in pressure on the diaphragm 89, to cause the force of the spring 90 to balance the total force of the signal pressure on the diaphragm. Thus when the pressure in diaphragm housing 88 increases from say atmospheric to some value between atmospheric and the maximum of the signal pressure delivered through pipe 8a, the piston will move upwardly until the bell crank and bar 95 have increased the tension in spring 90 suificiently to balance the force of the pressure acting on the diaphragm. When that occurs the valve will have been returned to its neutral position and the piston will come to rest; The piston will not move farther in the upward direction until there has beena further increase in the signal pressure in 8 pipe 8a which requires a decrease in flow in the tuyere rpe.

p If the signal pressure on the diaphragm decreases, the motion of the piston is downwardly to open its tuyere pipe valve wider as more flow is called for. In that event the bar 95 and the bell crank 92 relieve the tension in spring until the force of the spring is in balance with the force developed by the pressure on diaphragm 89. When that occurs the pilot valve 76 will again be returned to its neutral position and the piston will come to rest and remain at rest until there is either a further decrease or an increase of pressure in housing 88.

The bell crank 92 and angle bar therefore operate to control the length of the stroke of the piston for every increment of change in the signal pressure in line 8a. By adjusting the angle of the angle bar with reference to the side bar 70 or changing its shape, the length of stroke of the piston for any given change in signal pressure may be increased or decreased or the stroke may be caused to follow a particular function which has a relation to the flow in a tuyere pipe or the regulating charac teristics of the damper 6a.

The totalizing devices 9a to 9t being similar, a description of the totalizer in Fig. 6 will suflice for them all, but it will be designated 9a.

The totalizer 9a comprises a housing consisting of plate-like sections 97 and 98 and bell sections 99 and 100, respectively. The sections are bolted together by means of bolts 101, only one of which is shown, the bolts being uniformly spaced around the periphery of the members. A partition 102 is disposed between sections 97 and 98 and diaphragms 103 and 104 are disposed between sections 97 and 100, respectively, and 98 and 99, respectively. The margins of the diaphragms are securely clamped between their coacting housing members.

The central portion of diaphragm 103 is clamped between backing members 105 and 106 and the central portion of diaphragm 104 is clamped between a backing member 107 and a valve member 108. The valve member 108 is like a large headed bolt having a stem 109 that extends through the backing member 107 and the backing members 105 and 106 as shown. Between the backing members 105 and 107 is a cylindrical sleeve 110. That sleeve acts as a strut so that by threading a nut 111 on the stem 109 the central portions of the diaphragms 105 and 107 may be securely clamped between their respective backing members.

In order to provide pressure tight chambers between diaphragm 103 and the partition 102 and diaphragm 104 and the partition 102, the space surrounding the sleeve is sealed by bellows 112 and 113. As shown, the partition 102 has a passageway 114 leading to the atmosphere. The passageway 114 communicates with the space between the stem 109 and the sleeve 110 through an opening 115 in the sleeve.

The head of the valve member 108 is provided with an exhaust port 116 that communicates with the space between stem 109 and the sleeve 110 through a passageway 117.

In the housing member 90 is a valve stem 118 the lower end of which seats in the seat 116 and controls the exhaust port of the valve. The valve stem 118 operates in a valve body 119 having an inlet port 120. The inlet port 120 is controlled by a valve element 121 carried by the stern 118. The body 119 is provided with a fitting 122 to which the supply pipe 10a is connected. The valve stem 118 is urged in a direction to seat the element 121 on the inlet port 123 by-a relatively light spring 124. The diaphragm 104 operates against a relatively heavy compression spring 125.

The housing 100 has a neck 126 within which a compression spring 127 is contained, the tension of which is adjustable by means of a. bearing member 128 connected to the inner end of a screw 129 that is threaded through the outer closed end of the neck as shown. By turning the screw 129 inwardly or outwardly the spring force acting on the two diaphragms in a direction from right to left as seen in Fig. 6, may be adjusted.

The sections 97 and 98 are provided with inlet ports 130 and 131 and the neck 126 is provided with a port 132. The section 99 is provided with an outlet port 133 to which the outlet pipe 11a of Fig. 2 is connected.

In the particular arrangement shown in Fig. 2 only the pressure chamber supplied by port 131 is utilized, the ports 130 and 142 remaining uncovered and open to the atmosphere. Therefore, the output pressure at the port 133 leading to the pipe 11a will be a function of the pressure supplied through inlet port 131 and acting on diaphragm 1104 and the relative forces exerted on that diaphragm by springs 125 and 127, respectively. As the compression in spring 127 is increased thereby increasing the force acting from right to left as seen in Fig. 3, a higher pressure is required in chamber 135 within the housing member 99 to balance the spring force. Therefore, the outlet pressure to pipe 11a will be a function of the net forces exerted by springs 125 and 127 and the magnitude of the pressure acting on diaphragm 104 as delivered to port 131 by pipe 8a.

The ratio totalizer 12 as shown more in detail in Figs. 2. and 7, comprises a beam 140, mounted on a double acting frictionless fulcrum 141 that is secured to a frame 142. The totalizer includes a pressure chamber 143 formed by a housing 144 and a diaphragrm 145, the marginal edge of which is secured in pressure tight relation to the housing. Pressure may be supplied to the chamber 143 through a pipe 146. The diaphragm 145 acts through a push rod 147 on the right end of beam 140 as shown. The totalizer also includes a. chamber 148 formed by a housing 143 and a diaphragm 150 coupled to the beam by a valve member 151. The housing 149 is provided with a valve 152 that controls an exhaust port 153 and an inlet port 154 to which pressure is supplied through an inlet fitting 155.

When the beam 140 rocks in a clockwise direction, the valve 152 is actuated in a direction to uncover the inlet port 154, the exhaust 153 being then closed, whereby pressure is admitted into the housing chamber 148. The pressure increases in the chamber 148 until the force of that pressure acting on diaphragm 150 is suflicient to balance the applied clockwise force. If the forces acting on beam 140 are such as to cause it to turn counterclockwise about its fulcrum, the valve 152 closes the inlet port 154 and opens the exhaust port 151 allowing the pressure in the housing chamber 148 to exhaust to atmosphere until the force of the pressure on diaphragm 150 is in balance with the counterclockwise forces acting on the beam.

The ratio relay 12 also includes a pressure receiving chamber 156 formed by a housing 157 having a downwardly extending tubular chamber 158 and a diaphragm 15 9 clamped between the frame 142 and the open end of the housing 157. The diaphragm is operatively connected to beam 1'40 by a push rod 160 that passes through the diaphragm and is clamped in pressure tight fashion therewith by nuts 161. A spring 162 is secured at its upper end to the rod 160 and at its lower end to a traveling nut 163. The nut is engaged by an adjusting screw 165 threaded through the closed end of member 158 and into the nut 163. By turning the screw 165 the tension in the spring 162 may be adjusted. The spring 162 is adjusted to exert a downwardly acting force on the beam 140 to urge it in a counterclockwise direction.

The relay 12 may also be provided with a chamber 167 formed by a housing 168 having a diaphragm 169 secured thereto, the housing being supported by the base 142. The diaphragm engages the beam 142 by means of a stem 170 on which a nut is threaded to clamp to stem to the center of the diaphragm. Pressure may be admitted to the diaphragm if and when it is necessary to modify the operating characteristics of the relay by subjecting diaphragm 169 to either a fixed or a variable i 16 signal pressure. In the system shown in Fig. 2 no pres sure is supplied to diaphragm 169'.

The pressure in chamber 143 is established by the opening of valve 152 to the supply pressure or closing the inlet port and opening the exhaust port of the valve. The pressure in chamber 148 is referred to as the signal or sending pressure. That sending pressure is transmitted by pipe 13 to the diaphragm 43 of regulator 14. That pressure is also transmitted through a pipe .172 in which there is a needle valve 173, to diaphragm chamber 143. A volume chamber 174 is connected to pipe 172 at a location between the needle valve 173 and the housing chamber 143. The needle valve 173 .and the volume chamber 174 operate to provide automatic reset and rate action to device 12.

In the system as shown in Fig. 2 the tension in spring 162 is so adjusted that the beam 140 will be urged counterclockwise to maintain zero gauge pressure in chamber 148. Therefore, the pressure on diaphragm 161 must equal or exceed the downward force of the spring 162 before the beam 140 can tilt or turn clockwise to open the valve 152 and develop a sending pressure to the loading diaphragm of regulator 14.

So long as the pressure delivered by the totalizer 9t through pipe 112 to chamber 156 of device 12 is above the spring tension, the pressure in the pipe 13 will rise to and remain at a maximum value, that is at the maximum value of the supply source connected to the inlet of the valve 152. Whatever the value the signal pressure in pipe 13 may be, that pressure will load regulator 14 in such a manner that its output pressure to line 15 will be a function of the pressure in the bustle pipe 3 and the loading pressure in line 13.

As the loading pressure in line 13 increases, the output pressure of the regulator 14 increases. That output pressure is delivered as stated through pipe 15 to the loading diaphragms of regulators 5a to St as shown. Therefore, each of these regulators will cause the power cylinders 7a through 7t to so adjust the dampers or valves 6a to 6t towards closed position that the flow of hot blast from the bustle pipe will be distributed substantially equally among all the tuyere pipes to 2a through 2!, respectively.

The operation of the system is as follows. If it is to be assumed that tuyere pipe 2a is to be the base or reference pipe and that the damper or valve 6a is to be operated normally at a position near its wide open position, then the flow regulator 5a will be adjusted to cause its signal output pressure to pipe 8a to be at such a value as to cause the power cylinder 7a to adjust the damper towards that substantially wide open position. As the hot blast flows through the tuyere pipe 2a, that flow is measured by the diaphragm 211 of the device 5a and the valve 32 will be so positioned that the pressure in pipe 8a will be that required to operate the piston in power cylinder 7a downwardly and actuate damper 6a to its substantially wide open position. The signal pressure in pipe 812 is delivered to the chamber of the totalizer 9a supplied by port 131. Depending on the relative adjustments of the springs and 127, the output pressure of device 3a will be equal to or less than the supply pressure in pipe 10a. If the spring adjustments are such that when a relatively low pressure is added to that of the forces of the springs acting to open the valve port 123, the pressure in line 11a will be substantially equal to the supply pressure in pipe 10a. The output pressure of device 9a becomes the input pressure to device 9b.

Regulator 5b measures the flow in tuyere pipe 2b by sensing the pressure differential across the orifice 4b. It will therefore deliver an output signal pressure to line 8b which is transmitted to the pilot valve 77 of power cylinder 7b and to the chamber in the totalizer 9b served by port 131. The signal pressure developed by regulator 5b is one that tends to so position power cylinder 7b as to hold the flow in pipe 2b at the control a point of the regulator, as modified by the loading pressure on the loading diaphragm 43 of regulator b. The output pressure of the totalizer 9b as delivered to signal line 11b will be equal to the input pressure, that being the value of the output pressure of totalizer 9a. If the flow in pipe 2b is such as to so load the diaphragm 104 of the chamber supplied by port 131, that the output pressure to signal pipe 11b equals the pressure in pipe 1%, that indicates that the flow in tuyere pipe 2b is in the proper relation to the flow in pipe 2a. The output of device 9b as delivered to signal line 11b becomes the input pressure of the totalizer 9c.

The signal pressure from regulator 50 is supplied through port 131 of totalizer 90 by signal pipe 80. The signal in pipe 80 also goes to the diaphragm (89 of Fig. 5) of the pilot valve of power cylinder 7c and causes it to actuate damper 60 to the position required by the signal in pipe 80. That signal acting on diaphragm 104 of totalizer 90 determines the output pressure delivered to the next totalizer, which would be the totalizer supplied by the fiow responsive device 512 associated with tuyere pipe 2d and so on, until the signals reach the last totalizer for the furnace, that one being the totalizer 9t.

The totalizer 9t is supplied by the signal pipe 2s of the totalizer 9s which is the one associated with the tuyere pipe 2s. The pressure in pipe 2s is the supply pressure for the totalizer 9s. The diaphragm 104 of totalizer 9t is acted upon by the signal pressure in pipe 8t which is supplied by the escapement valve of the flow regulator 5t. That output signal pressure is delivered to the diaphragm of the pilot valve for regulator 7t and to the inlet port 131 of the totalizer 91. If the signal pressure as delivered to the final totalizer 9t is substantially equal to the signal pressure delivered to the first totalizer 9a, the flows in all of the tuyere pipes are equal. Furthermore, it may also indicate that all the available blast is being utilized by the blast furnace and that the supply is plentiful. Therefore, the ratio totalizer 12 being supplied with a pressure from the totalizer 91 that is greater than the force of spring 162, will deliver a pressure to the loading diaphragm regulator 14 and cause the walve 32 (Fig. 4) to move towards its wide open position. In that position the regulators 5a to St will be loaded to regulating points requiring the dampers to be moved more nearly towards their closed positions. When the output pressure of totalizer 9t is less than the spring force of spring 162, the control points of regulators 5a to St will be governed by the regulating points established by the pressure in the bustle pipe 3.

Having thus described the invention, it will be apparent to those of ordinary skill in the art to which the invention pertains that various modifications and changes may be made in the illustrated embodiment without departing from either the spirit or the scope of the invention.

Therefore, what is claimed as new and desired to be secured by Letters Patent is:

1. In a control system for effecting substantially equal distribution of blast among the tuyeres of a blast furnace having a bustle pipe to which hot blast is supplied, a tuyere pipe connecting each tuyere to the bustle pipe, means in each tuyere pipe for developing a pressure differential in accordance with the flow of blast through the same, and means in each tuyere pipe for adjusting the flow therethrough of a control system for effecting substantially equal rates in the tuyere pipes; said control system comprising a regulator for each tuyere pipe responsive to the pressure difference developed by said pressure differential means for developing a control force whose magnitude varies by and in accordance with the value of said differential, means responsive to the differential control force for so actuating said flow adjusting means as to maintain said differential substantially constant, each of said regulators having means whereby its regulating point may be adjusted, a series of totalizers, one of which is provided with a source of signal input power of substantially constant value, each totalizer having means for transmitting 'a signal output, said one totalizer responding to the output signal of a selected tuyere pipe regulator, the other totalizers being connected in cascade with the output of said one totalizer whereby the respective signal supplies for the totalizers following said one totalizer are constituted by the outputs of the respective preceding totalizers, each of said totalizers being connected to receive as its input signal the output signal of its associtated tuyere pipe regulator, and means responsive to the output of the last one in the series of totalizers for developing a control force that is delivered to the regulating point adjusting means of said tuyere pipe regulators for changing the control points thereof in accordance with the supply of hot blast available in the bustle pipe.

2. A control system as in claim 1 in which a regulator is provided that is responsive to the pressure in the bustle pipe and to the control force developed by the means which is responsive to the output of said last totalizer, for developing a control force whose magnitude is such as to effect the adjustment of the control points of all the tuyere pipe regulators to values corresponding to the supply of hot blast in the bustle pipe.

3. The control system as in claim 1 in which the tuyere pipe regulators are loaded regulators and that the means responsive to the output of the last totalizer in the series is a loaded graded regulator.

4. The control system as in claim 1 in which each totalizer comprises a housing having a chamber provided with a diaphragm, a valve actuated by the diaphragm for developing a pneumatic output signal to which the diaphragm responds, and an input connection for receiving the output of a tuyere pipe regulator, the output signal being proportional to the input signal.

5. The control system as in claim 1 in which the means that responds to the output of the last totalizer is a regulator having a beam mounted on a fulcrum, a pair of housings at one end in the beam, each having a diaphragm and chamber, the diaphragms engaging the beam in opposing relation, a valve actuated by the beam for developing a signal pressure that is connected to both chambers, there being a restriction in the connection to one of the chambers providing rate response and automatic reset, said regulator having another chamber at the other end of'the beam and provided with a diaphragm connected to the output of the last totalizer, said latter diaphragm acting on the beam in a direction to open said valve and being urged in a direction opposed to the direction in which the pressure acts thereon, with such force that the valve is closed until the input signal exceeds said urging force.

6. In a control system for effecting substantially equal distribution of blast among the tuyeres of a blast furnace having a plurality of tuyeres through which hot blast is supplied to the furnace charge, a bustle pipe to which hot blast is supplied, a tuyere pipe connecting each tuyere to the bustle pipe, means in each tuyere pipe for developing a pressure differential in accordance with the flow through the same, and means in each tuyere pipe for adjusting the flow therethrough in accordance with the signal pressure developed by the regulator associated with each pipe; said control system effecting substantially equal distribution of blast through each tuyere pipe and comprising a regulator for each tuyere pipe that is responsive to the pressure difference across its pressure differential developing means for generating a control force that varies in accordance with the flow in said pipe, means actuated by said control force for regulating the blast flow to a value that tends to maintain said pressure differential substantially constant, each of said regulators being provided with means for changing the regulating points thereof, one of said regulators being initially adjusted to maintain its flow regulating means at a substantially maximum flow position, a

totalizer for each tuyere pipe, the output signal of the regulator associated with the tuyere pipe which is controlled to substantially maximum flow being supplied to its associated totalizer, said totalizer having an input signal supply of substantially constant value, the other totalizers being so connected to each other and to said first totalizer that the output of one is supplied to the signal supply input of the other, the signal outputs of the tuyere pipe regulators after the first one being supplied to the inputs of their respective totalizers whereby the magnitude of the output or" any one totalizer can never exceed the magnitude of its signal supply or the output of the next preceding totalizer, a regulator responsive to the bustle pipe pressure for adjusting the regulating points of each tuyere pipe regulator, and means responsive to a predetermined maximum output of the last totalizer for modifying the control point of the bustle pipe regulator and causing each tuyere pipe regulator to operate at a lower pressure differential regulating point, said tuyere pipe regulators operating at maximum differential points when the bustle pipe pressure is below a predetermined value and the output of the last totalizer is below a predetermined value.

7. In a control system for effecting substantially equal distribution of air flow among a plurality of pipes which are supplied by a common duct, said pipes discharging at spaced points into a bed of variable resistance to flow and means in each pipe for developing a pressure difference; said control system comprising a regulator for each branch pipe responsive to the pressure difierence developed by said pressure differential means, for developing a signal whose magnitude is proportional to said pressure diiference, each regulator having means whereby its control point may be adjusted, means in each branch pipe for adjusting the flow therein, means associated with each branch pipe and operated by the control signal of the branch pipe regulator for so operating the flow adjusting means that the pressure difference in each pipe tends to be maintained substantially constant at the control point of the regulator therefor, each branch pipe being provided with repeater means responsive to the output signal of its branch pipe regulator, one of said repeater means having a signal source of supply of substantially constant value for developing an output signal that is proportional in magnitude to the branch pipe signal input thereto, the other of said repeater means being connected in cascade with their respective supply inputs connected to the output signal of a preceding repeater, a regulator connected to the output of the last repeater in the cascade, said regulator having means rendering it responsive to develop a signal when the output signal of the last repeater in the cascade reaches a predetermined value, a control point adjusting regulator responsive to the bustle pipe pressure and the output signal of the cascade responsive regulator, for adjusting the control points of the branch pipe regulators, said cascade responsive regulator being biased to nonsignal transmitting position so long as the input signal to any one of the repeaters is below the value at which the cascade responsive regulator is operative to transmit an output signal.

8. A control system for maintaining substantially equal flows of hot blast in the tuyere pipes of a blast furnace, each of the tuyere pipes being provided with an orifice and supplied with blast from the furnace bustle pipe, and having a flow regulating valve therein, said system comprising a positioner for each valve for actuating the same, a first regulator for each positioner responsive to the pressure drop across the orifice in its associated pipe for so actuating the valve thereof that the pressure difference across the orifice is maintained at the control point of the regulator, each positioner regulator being provided with means for changing the control point thereof, a second regulator for transmitting a control force to each positioner regulator and changing the control points thereof in response to changes in the bustle pipe pressure, said second regulator having means whereby its regulating point may be changed, a third regulator for imposing a control force on the regulating point changing means of the bustle pipe regulator, a series of totalizers, one of which is provided with a source of signal input power of substantially constant value, each totalizer having means for transmitting a signal output, said one totalizer responding to the output signal of a selected tuyere pipe regulator, the other totalizers being connected in cascade with the output of said one totalizer whereby the respective signal supplies for the totalizers following said one totalizer are constituted by the outputs of the respective preceding totalizers, each of said totalizers being connected to receive as its input signal the output signal of its associated tuyere pipe regulator, and means responsive to the output of the last one in the series of totalizers for developing a control force for rendering the third regulator nontransmitting when the signal output of any one of said first regulators is below a predetermined minimum value and rendering the same transmitting when the signal output of each of said first regulators is above said minimum value.

Burke June 8, 1937 Jones Dec. 18, 1956 

